Michal Hocko wrote: > On Thu 19-02-15 13:29:14, Michal Hocko wrote: > [...] > > Something like the following. > __GFP_HIGH doesn't seem to be sufficient so we would need something > slightly else but the idea is still the same: > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 8d52ab18fe0d..2d224bbdf8e8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2599,6 +2599,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > enum migrate_mode migration_mode = MIGRATE_ASYNC; > bool deferred_compaction = false; > int contended_compaction = COMPACT_CONTENDED_NONE; > + int oom = 0; > > /* > * In the slowpath, we sanity check order to avoid ever trying to > @@ -2635,6 +2636,15 @@ retry: > alloc_flags = gfp_to_alloc_flags(gfp_mask); > > /* > + * __GFP_NOFAIL allocations cannot fail but yet the current context > + * might be blocking resources needed by the OOM victim to terminate. > + * Allow the caller to dive into memory reserves to succeed the > + * allocation and break out from a potential deadlock. > + */ We don't know how many callers will pass __GFP_NOFAIL. But if 1000 threads are doing the same operation which requires __GFP_NOFAIL allocation with a lock held, wouldn't memory reserves deplete? This heuristic can't continue if memory reserves depleted or continuous pages of requested order cannot be found. > + if (oom > 10 && (gfp_mask & __GFP_NOFAIL)) > + alloc_flags |= ALLOC_NO_WATERMARKS; > + > + /* > * Find the true preferred zone if the allocation is unconstrained by > * cpusets. > */ > @@ -2759,6 +2769,8 @@ retry: > goto got_pg; > if (!did_some_progress) > goto nopage; > + > + oom++; > } > /* Wait for some write requests to complete then retry */ > wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, HZ/50); > -- > Michal Hocko > SUSE Labs > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
